The objectives of the proposal are: (1) The characterization and comparison of the membrane properties of the unfertilized and fertilized eggs with respect to the influx and efflux of Na, K ions, Cl minus, and Ca2 ion, ion permeabilities (passive diffusion and exchange diffusion), and ion transport (pump mediated). (2) The comparison of intracellular ion concentration patterns of the unfertilized and fertilized eggs, and the definition of these patterns in terms of the measured fluxes. (3) The comparison of the unfertilized and fertilized eggs with regard to the intracellular compartmentalization of ions. (4) The investigation of the relationship of the membrane potentials of the unfertilized and fertilized eggs, and the changes observed after insemination, to the measured permeabilities, ionic concentration, and ion transport. (5) The examination of the effects of parthenogenetic agents and chemical carcinogens on the ion fluxes, ion compartmentalization, and the ion content of the eggs. BIBLIOGRAPHIC REFERENCES: Chambers, E.L., and Dimich, R.A. A Na ion requirement for cytoplasmic and nuclear activation of sea urchin (Lytechinus variegatus) eggs by sperm and by divalent ionophores. J. Gen. Physiol. 66: 9a, 1975. Chambers, E.L. Potassium exchange in unfertilized sea urchin (Arbacia punctulata) eggs. Biol. Bull. 149: 422-423, 1975.